Specimens from human ocular tissues with various diseases such as uveitis, retinal disease, conjunctival and corneal diseases, metabolic genetic diseases, and tumors are studied using immunohistochemical and in situ hybridization techniques as well as light and electron microscopic evaluation. In uveitis, immunocompetent cells and lymphokines are valuable adjuncts to clinical diagnosis, as well as determinants of disease course and prognosis. In nonuveitic conditions, alteration of cellular membrane surface markers and intracytoskeleton of the ocular resident cells may imply damage and abnormalities in these diseases. Elucidating the role of the relationships between infiltrating inflammatory or malignant cells and other resident cells in the clinical behavior of various diseases will increase our understanding of human ocular disorders.